Coal seam gas, also known as coal bed methane, is natural gas that is adsorbed on coal in coal beds and is a valuable natural resource. To extract coal seam gas, the adsorbed natural gas must be released from the coal. To do so, a well is drilled into the coal seam, which reduces the pressure of the seam and causes the natural gas to be released. The natural gas may then be collected.
Typically, coal seam gas is collected in conjunction with water, called “brine” or “produced water.” After extraction, brine may be utilized in other processes or prior to release or reuse, the brine undergoes various treatment processes, such as those for removing contaminants. Because brine from coal seam gas contains a substantial amount of suspended and dissolved contaminants, such as hardness and silica, it is likely that scaling or fouling will occur on treatment equipment absent reducing the concentrations of these species. For example, one particularly harmful scaling contaminant found in brine is silica. Unless silica is removed via a pretreatment process, silica will form damaging scale on equipment used in brine treatment, such as evaporators. Some of the coal seam gas brines also contain a substantial amount of dissolved alkalinity and chloride. It is desirable to recover these components as commercial products rather than leaving them as waste for disposal. Removal of silica is advisable for recovering useful products.